Compressor regulator



Sept. 29, 1953 P. H. DAVEY COMPRESSOR REGULATOR 3 Sheets-Sheet 1 Filed Dec. 19, 1946 mvslvrdn PAUL H. DAVEY WtE'QOM/ ATTORNEYS P 1953 P. H. DAVEY COMPRESSOR REGULATOR 5 Sheets-Sheet 2 Filed Dec. 19, 1946 fivvewron PAUL H. Dnvsr A rramvcrs Sept. 29, 1953 Filed Dec. 19, 1946 P. H. DAVEY COMPRESSOR REGULATOR 5 Sheets-Sheet 3 IIIVVENTOR PA UL H. DAVE) viwwwaflmaw ATTORNEYS Patented Sept. 29, 1953 UNITED STATES PATENT OFFICE.

COMPRESSOR REGULATOR Paul H. Davey, Kent, Ohio Application December 19, 1946', Serial No. 717,103

2 Claims.

This invention relates to improvements in compressor regulators and more particularly, to improvements in control means for the prime mover driving a compressor and responsive to the requirements for compressed fluid.

An object of the present invention is to provide a device for controlling the speed of a (30mpressor responsive to the demand for gaseous fluid as it is being used.

Another object of the.present invention is to provide a device responsive to flow in a stream of compressed gas or air, and an operative connection between such a device and a prime mover for operating the compressor so that as the device is affected by greater or less flow of fluid in the line of the prime mover is speeded up or slowed down respectively.

Another object of the present invention is to provide, in combination with the above mentioned control device, a lost motion arrangement whereby the compressor may beslowed down independently of the position of said control device when such slowing downis desirable for some other reason such as, for instance, if the container for compressed fluid reaches a predetermined pressure.

Other objects and advantages of the present invention include novel arrangements of the parts and control connections for carrying out the above mentioned purposes as will appear from the accompanying drawings and description, and the essential features of which will be set forth in the appended claims.

In the drawings,

Fig. 1 is a side elevational view of a known type of air compressor equipped to utilize my invention;

Fig. 2' is a diagrammatic view showing the essential operating parts of Fig. 1 arranged so as to show their operative relationship with each other. The control device, responsive to flow of compressed air, is greatly enlarged relative to the other parts;

Fig. 3 is another view of a portion of Fig. 2 showing a different position of the parts;

Fig. 4 is a modified form of device for carrying out a portion of the functions described in connection with Figs. 2 and 3 and omitting the arrangement for slowing down the compressor upon the reservoir reaching a predetermined pressure;

Fig. 5 shows a further modification including a difierent arrangement responsive to flow in the compressed air line and an operative connection between the same and the prime mover control member including electrical connections;

Fig. 6 is a sectional view through a still further modification of my invention;

Fig. 7 is a sectional view of the same. taken along the line '|-1 of Fig. 6; while Fig. 8 is a transverse sectional view taken along the line 88 of Fig. 6.

I have chosen to disclose and describe my device as applied to a known type of air compressor driven by an internal combustion engine, but it should be understood that my control apparatus is equally adapted for use with any gaseous compressor and with other types of prime movers, as will be readily understood by those skilled in this art.

In Fig. 1 I have shown one form of compressor apparatus adapted to utilize my invention. On a wheeled chassis I0 there is mounted an internal combustion engine H which drives a compressor [2, two cylinders of which are shown at Ma and 1 I221. The air to be compressed enters. through an air cleaner I3 and after compression, passes through the lines 14 to line l5, and then to a reservoir [6. The air to be used is drawn from reservoir [6 through line H which passes through the housing It; of the control device to outlets l9 and 29 for use at opposite sides of thevehicle. The fuel supply for the engine H. passes through a carburetor indicated at 2| and the supply of fuel is controlled by the position of armv 2la which is connected by a rod 22 with my-improved control apparatus.

Most of the prior devices known to me, controlling the prime mover driving a compressor of this type, operate in response to the pressure in a reservoir such as that shown at It. In a simple form of device the compressor is unloaded, or the prime mover driving the same is caused to slow down (or both) when the pressure in the reservoir reaches a predetermined value. In another well-known control the compressor is progressively slowed down in several steps as the pressure in the reservoir approaches a predetermined value. One of the difiiculties with these devices is that they never supply the full volume of compressed air at the full pressure for which the apparatus is designed. In other words, the compressor is driven at full speed only when the pressure in the receiver is something less than the full pressure for which the apparatus is designed.- One of the advantages of my invention is that it supplies a full volume of fully compressed air When full volume is demanded, and supplies at all times a substantially steady volume at the. same rate as demanded.

As indicated in Fig. 2, I have illustrated a compressor cylinder, say [2a, of the free air unloading type. The compressed air normally passes out of the cylinder through valve 23 to the line l4 on its Way to the reservoir IS. A line 2 leads from the reservoir through a pressure responsive valve 25 to line 26 and thence through passageways 21 and 28 in the housing 29, and through a spring pressed check valve to line 3| which leads to chamber 32 above piston 33 which controls the unloading valve 36 which in turn is normally held closed by the spring 35. The spring 25a of valve 25 is set for a predetermined value so that when reservoir [6 has reached a predetermined pressure it will drive the piston 25b backward or toward the right, as viewed in Fig. 2, so as to uncover port 36 leading to line 28. There will now be a flow of compressed air through valve 39 and line 3! to the chamber 32. This drives piston 33 downwardly opening valve 34 so that the compressor is unloaded and the pistons move up and down without compressing any air. The operation of this unloading valve is tied in with my novel control, as will later appear.

Means is provided within the housing l3, responsive to the demand for compressed air, to speed up the engine ll when more air is being used, or to slow down the engine when less air is being used. This device is placed in line i? which leads out of the reservoir it, but it should be understood, that the principle of my invention permits its use in any line, subject to the flow of air required by the tools or other apparatus for its utilization.

To accomplish the above purpose, I have formed the passageway 18a, of the housing 58, into a cylinder which is fitted with a reciprocating piston 31. This piston is connected with the rod 22 which controls the carburetor 2i in a novel fashion. The piston rod 31a has a slot 3% in its outer end in which rides a pin 38 which is integral with a stop collar 39 which in turn is threaded on a sleeve 4! the outer end or" which is pivotally connected with a link 41 which in turn operates a bell crank 42 which is pivotally connected with the rod 22. The sleeve 49 carries a piston 48a which is mounted for reciprocation in the hollow portion of the housing 29. The piston a is urged toward the right as viewed in Figs. 2 and 3 at all times by a light spring 43. The piston 31 is urged toward the left at all times by a strong spring 44. There are provided a plurality of openings S'lc through the walls of piston 3! and adapted to be uncovered progressively as piston 31 moves toward the right, as viewed in Figs. 2 and 3. Here, the cylinder wall I8a is imperforate and the piston 31 is perforated. Obviously, this construction could e reversed so that the piston 3"! was imperforate and uncovered flow openings in the cylinder wall l8a as the piston moved toward the right. In either case, when air is used out of either of the branches [9 or 20 the pressure becomes less on the right-hand face of piston 31 so that the greater pressure on the left-hand face forces piston 3'! toward the right against the action of spring 44 until sufficient of the openings at 370 are uncovered to permit the flow of air required The greater the demand for air, the farther piston 3'. will move toward the right and then more of the openings 310 will be uncovered. With the spring 43 maintaining pin 33 in the right-hand end of slot 3%, obviously the sleeve 48 will move back and forth responsive to the movements of piston 31 and the connection with the carburetor is such that it speeds up the engine :5 as rod 22 moves upwardly. Thus, as piston 37 moves toward the right it increases the speed of engine H and as piston 31 moves toward the left it causes a slowing down of engine H. Thus, in normal operation, the greater the requirement of compressed air, the faster the engine H will drive the compressor. In practice, the parts are so constructed that the engine drives the compressor at a rate that about equals the demands for air. This is in contrast with the usual custom of alternately driving the compressor at full speed and then causing it to idle.

The operation of the unloading valve will now be apparent from a study of Fig. 3. Here the pertinent parts of Fig. 2 have been reproduced, it being understood that the other connections are like those already described. Whenever the pressure in reservoir [6 reaches a predetermined value so that it is transmitted through line 24 to the piston valve 25 at a great enough pressure to overcome spring 25a, piston 25b will. be moved to the position shown in Fig. 3 and compressed air will flow through port 38 and line 26 to the housing 29. Flowing through passageway 21 it will fill the chamber 2% driving piston 40a toward the left, as shown in Fig. 3 against the tension of spring 43. Regardless of the position of piston 3?, piston rod 37a and the slot 3711, the sleeve 40 will move toward the left impelled by piston 4811 until stop collar 39 strikes the housing 28, as shown in Fig. 3. The lost motion of pin 33 in slot 315 permits this action to take place. This movement of sleeve 48 carries link 4! toward the left so as to move bell crank 32 in a clockwise direction which pulls down on rod 22 so as to operate the carburetor 2 i to slow down the engine l 1. Thus, at the same time that air flows through check valve 30 and line 3! to unload the compressor it moves piston 43a to cause a slowing down of the engine ll.

Regardless of the position of piston 31, if the pressure in receiver It falls below a predetermined point when the parts are in the position of Fig. 3, the spring 25a will overcome the air pressure acting upon piston 25b so as to return it to the position shown in Fig. 2 so that line 25 then communicates through port 36 with the chamber 250 and exhaust port 25d. Immediately, the air pressure is relieved in passageways 21 and 28 and the ball check valve 30 will close. The air is momentarily trapped in line 3| and chamber 32 so that valve 34 will remain open for a short period of time. Air is immediately evacuated from the chamber 2911 as spring 43 returns piston 40a from the position of Fig. 3 to that of Fig. 2. Regardless of the position of piston 31 this will speed up the engine by again moving rod 22 upwardly as previously described. As piston 49a moves toward the right it uncovers a small port 45. This permits the escape of trapped air from line 31 and chamber 32 so as to permit spring 35 to close valve 34 and the compressor will again compress air. This arrangement causes the engine to speed up slightly before the load is placed on the compressor.

In Fig. 4 I have shown a modification wherein the control device is arranged to speed up the compressor when more air is used and to slow down the compressor when less air is used but without the features described in connection with the unloading valve 34. In other words, the piston 31 moves toward the right as more air is required at the outlets I9 and 25! so as to cause the piston rod 46 to move toward the right. Here the piston rod is connected with link 4| which leads through hell crank 42 to the car buretor control rod 22 as previously described. The greater the requirement of air, the more holes 41 will be uncovered andthe farther piston 31' will move toward the right to speed up the compressor. Obviously, when less air is used, spring 44' will move piston 31 toward the left, a viewed in Fig. 4,, until the number of openings 41 uncovered is just suflicient to take care of the air required in use. This will slow down the compressor to that speed necessary to supply the demand for air.

In Fig. 5, I have shown a modification wherein a different sort of device is provided in the line I! subject to the quantity of air flowing through line 48 to a point of use. I have shown a Venturi tube 49 having a throat 49a. Pressure lines 50 and 51 lead respectively from the throat and mouth of the Venturi tube to a differential pressure manometer 52 filled with mercury or other electrically conductive liquid. In one leg of the manometer I have mounted resistance 53 so that the greater the flow through the Venturi tube 49 the more of resistance 53 will be exposed, in other words, its electrical resistance value will be increased. This resistance is in one leg of a Wheatstone bridge arranged so that the product of 53 times 54 is equal to the product of variable resistance 55 times 56. The current for the bridge is supplied through battery 51. A galvanometer armature is pivotally connected at 59 and carries contacts 60 adapted to close an electric circuit from source LI through motor 6| to the source L2. The motor is reversible so that it is driven in opposite directions depending on the direction of movement of the contacts 60. This is a well known form of device for causing motor 6| to follow the variations of resistance 53. The motor is connected through shaft 62 with arm 63 so as to vary the resistance 55 to bring the bridge into balance after each variation of resistance 53. Motor Bl through shaft 62 also oscillates the lever arm 64 which is connected to the carburetor control rod 22 previously described.

The operation of the modification of Fig. should now be apparent. As flow increases in the Venturi tube 49 the electrical value of resistance 53 is increased causing motor 6| to operate in a direction to increase the value of resistance 55 in the bridge circuit. This causes lever arm 64 to move in a counterclockwise direction which raises rod 22 and speeds up the engine I I. Conversely, when the flow is decreased in the Venturi tube the motor 6| will move in the opposite direction so as to pull down on rod 22 and cause a slowing down of the compressor.

It will be noticed in Fig. 5 that line 5! leading to the manometer is subject substantially to the static head in the line I! connected with the compressor receiver. It is a well known fact that in a Venturi tube the static head at the outlet side of the Venturi tube is substantially the same as at the inlet side thereof. The line 50 connected to the throat of the Venturi tube is a rough measure of the velocity head developed at the throat. 49a corresponding to the flow of fluid through the throat of the tube. Thus, the manometer of Fig. 5 is a differential device having two sides, one side being substantially responsive to a pressure the same as the receiver pressure and the other side being responsive to a pressure which is generally in step with the velocity of the compressed fluid flowing to the using device connected to the pipe 48.

The modification shown in Figs. 6, '7 and 8 shows still another manner in which my inverttion may be utilized. The line H previously described is connected to a valve body which pro vides a valve seat 66 which is adapted to be closed by a butterfly valve 61 which is rigidly secured to a shaft 68 rotatably mounted in the valve body. Suitable packing is provided at 69- where the shaft emerges from the valve body. A lever arm 10 is mounted tomove with the shaft 68 responsive to the movement of valve 61. the arm I0 with the bell crank 42 previously described. A spring 12 held between a bracket 65a on the valve body and a collar 13 on the link H normally urges the valve 61 toward closed position.

The operation of this last described modification should now be apparent. When air is called for by a tool connected to one of the outlets 14, valve 61 is opened by the greater pressure on the left-hand side thereof as viewed in Figs. 6 and '7, so that it moves to the dot-dash position indicated in Fig. 7. The amount of opening of the valve 61 will be roughly proportional to the volume of air demanded by the working tool. Therefore, the greater the demand for air the more valve 61 will be moved in a counterclockwise direction, as viewed in Fig. 7, and the more the link 22 will be raised in the direction to speed up the engine driving the compressor. Thus, at any given demand for air, the engine will be speeded up to approximately the point to fulfill that air demand without the repeated sudden acceleration and deceleration generally encountered in compressors using presently known types of controls.

What I claim is:

1. In apparatus comprising a gaseous fluid compressor and a prime mover for operating the same and a line for the flow of compressed gaseous fluid for use, the combination of a control member controlling the speed of said prime mover, a Venturi tube in series in said flow line, a differential pressure manometer having its legs in communication respectively with the throat and mouth of said tube, an electrically conductive liquid in the legs of said manometer, an electrical resistance partially submerged in said liquid in one of said legs, an electric motor for moving said control member, and electrical means responsive to variations in said resistance for operating said motor, said manometer and resistance being connected to cause said motor and control member to increase compressor speed as flow rate increases through said Venturi tube.

2. In apparatus, comprising a gaseous fluid compressor and a prime mover for operating the same and a receiver for storing the compressed fluid and an outlet line from the receiver for the flow of compressed fluid for use, the combination of a control member controlling the speed of said prime mover, a diflerential device operatively connected with said control member to control the speed of said compressor in step with the flow of compressed fluid for use, said differential device having two sides balanced against each other, one side thereof in the outlet line of said receiver substantially responsive to receiver pressure and the other side thereof responsive to a pressure generally in step with the velocity of compressed fluid for use, and said device responsive to the differential of said pressures on its two sides, said differential device being connected to cause said pressure differential to increase with increase in fluid flow rate from said compressor, and means for causing A link H connects.

7 said device to move said control member to cause increase in compressor speed as said fluid flow rate increases and to cause decrease in compressor speed as said fluid flow rate decreases.

PAUL H. DAVEY.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 779,623 Porter Jan. 10, 1905 1,017,509 Callan Feb. 13, 1912 1,154,467 Wilkinson Sept. 21, 1915 Number 10 Number Name Date Banner Apr. 10, 1917 Sherbondy June 13, 1922 Crago May 23, 1933 Baker Aug. 29, 1939 Slater June 19, 1945 Jepson et a1. Jan. 30, 1951 FOREIGN PATENTS Country Date Great Britain 191'. Germany 1910 Germany 1930 

